Steric effects of alkyl dibenzothiophenes: The root cause of frustrating efficacy of heterogeneous desulfurization for real diesel

High-carbon alkyl dibenzothiophenes (DBTs) in real diesel are difficult to remove. Their steric effect has been studied and identified as the controlling factor in heterogeneous catalytic oxidation desulfurization (ODS) process. Mixed alkyl DBTs (C₂-DBT, C₂-C₂-DBT, C₃-DBT, and C₃-C₃-DBT) were synthesized via DBT's Friedel–Crafts alkylation, and their reactivity is DBT > C₂-DBT > C₂-C₂-DBT > C₃-DBT > C₃-C₃-DBT. C₃-DBT, C₂-C₂-DBT, and C₃-C₃-DBT can be hardly removed by any of three efficient heterogeneous ODS processes, but are removed efficiently in a homogeneous ODS process of HAc-HPW-H₂O₂, which contrasts the great importance of their steric effects in heterogeneous catalytic process. Thus, the frustrating efficacy of various ODS processes for real diesel is likely originated from the unidentified high-carbon alkyl DBTs and their least reactivity in heterogeneous catalytic systems. And, the steric hindrance is diminished greatly in a homogeneous catalytic process. The results are instructive for the development of new catalysts and catalytic ODS processes for real diesel.     

Isolation and identification of constituents of Jasminum auriculatum (Vahl) leaves

Jasminum auriculatum (Vahl) (family: Malvaceae) widely grown in India was analysed for its fatty acids and waxy constituents. Straight-chain hydrocarbons (C₂₀-C₃₄), fatty acids (C₁₄-C₂₃) and fatty alcohols (C₂₁-C₃₂) were found in the 95% aqueous ethanol extract of the leaves of the plant. Malvalic acid was the only cyclic acid identified. Hydrocarbons (C₂₉ and C₃₁), fatty acids (C₁₆, C₁₈, C_18:1, C_18:2, C_18:3 and C₂₂) and fatty alcohols (iso-C₂₆, C₂₈ and C₃₀) were the major components. Four polyalcohols, namely D-mannitol, xylitol, inositol and sorbitol, have also been found in the alcoholic extract of the leaves.     

Studies of a Supported Titanium Catalyst System Using Magnesium Dichloride–Alcohol Adduct

Magnesium dichloride reacts with aliphatic alcohols [ROH; R = n-C₂H₅, n-C₃H₇, i-C₃H₇, n-C₄H₉, i-C₄H₉, t-C₄H₉, n-C₅H₁₁, n-C₆H₁₃, C₆H₁₂(C₂H₅)] to form well-defined solid adducts. Compositional analysis of adducts indicates that the stoichiometric ratio of magnesium dichloride to alcohol depends on length of alkyl group and nature of isomeric alcohol. Magnesium dichloride-2-ethyl-l-hexanol adduct was treated with diphenyldichlorosilane in the presence of dibutylphthalate to obtain active magnesium dichloride support. The titanation process of active magnesium dichloride gives supported magnesium–titanium catalyst (Mg–Ti). The catalyst was characterized by compositional analysis and specific surface area measurements. Performance of the catalyst for polymerization of propene was evaluated with triethylaluminum (TEAL) and phenyltriethoxysilane (PES) as cocatalyst. The yield and isotacticity of the polymer is governed by polymerization parameters such as Si/A1 ratio and polymerization time.     

Leaf wax ofPortulaca oleracea

Wax coating the leaves and stems ofPortulaca oleracea consists of hydrocarbons (21%), esters (53%), acids (2%), alcohols (4%), diol monoesters (2%), and unidentified material (15%). Lesser amounts of esterified and free β-amyrin and lupeol, stigmast-4-en-3-one and free diols also are present. The principal component of the hydrocarbons is C₃₃. The C₄₀-C₅₆ esters are C₂₂-C₂₈ alcohol esters of C₂₀-C₂₆ acids; free alcohols are C₂₂-C₃₀; free acids are C₁₆-C₃₆; diols of diol monoesters and free diols are C₂₀-C₂₆. Presented at the AOCS Meeting, Ottawa, September 1972. NRCC No. 14037.     

Effects of CNTs content on microstructure and mechanical properties of Cnt/α-Al2O3 and Cnt-Csf/α-Al2O3 composites

In this work, CNTs and short carbon fiber reinforced α-Al₂O₃ matrix composites (i.e., C_nt/α-Al₂O₃ and C_nt-C_sf/α-Al₂O₃) were prepared by sol-gel dispersing method followed by hot pressing process. Effects of CNTs content on the mechanical properties of C_nt/α-Al₂O₃ and C_nt-C_sf/α-Al₂O₃ composites were investigated and the inter- and transgranular fracture mechanisms in C_nt-C_sf/α-Al₂O₃ composites were analyzed. The hardness and relative density of C_nt/α-Al₂O₃ and C_nt-C_sf/α-Al₂O₃ composites slightly decrease as CNTs content increases. The flexural strength and fracture toughness monotonically increase with the increase in C_nt content for both C_nt/α-Al₂O₃ and C_nt-C_sf/α-Al₂O₃ composites. Addition of C_sf and CNTs into α-Al₂O₃ matrix results in a bimodal grain size microstructure of C_nt-C_sf/α-Al₂O₃ composites, which accounts for the unique fractograph and the enhanced toughness of C_nt-C_f/α-Al₂O₃ composites. The flexural strength and fracture toughness of C_sf5-nt06 composite are 465 MPa and 7.08 MPa/m², 37% and 13% higher than that of C_nt06, and 42% and 34% higher than that of C_sf5, respectively.     

Catalytic oxidation of hydrocarbons over Co3O4 catalyst prepared by CVD

The total oxidation of C₂H₂, C₃H₆, C₃H₈, n-C₄H₈, n-C₄H₁₀ and i-C₄H₁₀ was studied in a monolithic flow reactor under temperature-programmed mode and highly diluted conditions. The non-catalytic combustion of the investigated hydrocarbons leads to a substantial formation of CO and traces of methane at intermediate temperatures. This drawback was suppressed upon the deposition of a thin layer of Co₃O₄ on the monolith and all investigated hydrocarbons tend to light off at 250–290 °C. The apparent activation energy was found to exhibit a linear correlation with the C–H bond dissociation energy, indicating that the C–H activation is still the rate-limiting step.     

Combined hydration of tricalcium silicate and β-dicalcium silicate

The mutual interaction of tricalcium silicate (C₃S) and β-dicalcium silicate (β-C₂S) in their combined hydration was studied. The rate of β-C₂S hydration was accelerated significantly in the presence of C₃S. The rate of C₃S hydration was retarded, but only in the presence of large amounts of β-C₂S. The stoichiometric composition and the pore structure of the hydrates formed was altered only unsignificantly when both compound hydrated simultaneously.     

Hydration of B2O3-stabilized α′-and β-modifications of dicalcium silicate

Paste hydration of B₂O₃-stabilized α′- and β-C₂S was studied at reaction times between 5 hours and 28 days. Data on the degree of hydration determined by X-ray diffraction at different ages were used to evaluate hydration rate constants. The higher rate of α′-C₂S hydration resulted in the higher compressive strengths of the α′-C₂S-alite paste as compared with the β-C₂S-alite paste. Differences in crystal imperfections of the two C₂S-polymorphs were determined using electron microscopy and electron diffraction.     

Modification of butadiene–acrylonitrile and styrene–acrylonitrile copolymerizations in emulsion systems

Modification of acrylonitrile in copolymerizations with butadiene and with styrene in hot and cold emulsion recipes has been studied. Series of primary, secondary, and tertiary mercaptans in addition to several miscellaneous modifiers were tested. Kinetically the rate data for the monomer pairs containing acrylonitrile better fit first-order plots than the curves obtained for an ideal emulsion polymerization. In this study all modifier depletions in nitrile systems were plotted as log mercaptan versus log conversion and the slope of the curve was taken as the transfer constant. Normal mercaptans were inefficient modifiers in nitrile systems as determined in polymerization and depletion experiments. Secondary mercaptans, 2-nonyl, 2-decyl, and mixtures in this molecular weight range, were promising modifiers for low temperature (5°C.) nitrile systems. 2-Nonyl mercaptan gave enhanced modification by incremental addition of the modifier indicating this procedure could be used to advantage in preparing nitrile rubbers. The series of tertiary mercaptans from C₁₃ to C₇ showed an improvement in modification of low temperature nitrile systems as the molecular weight decreased. A plot of the data on a molar basis shows that the optimum modifier falls in the C₉–C₈ range. The optimum transfer constant for the most efficient modification of 70/30 and of 80/20 butadiene–acrylonitrile polymerizations at 5°C. terminated at 60% conversion is 2. Depletion data show that the transfer constant for a mercaptan decreases as the nitrile content in mixtures with butadiene increases. The properties of the vulcanizates of the 70/30 and 80/20 butadiene–acrylonitrile polymers prepared in the presence of low molecular weight mercaptans were equivalent to or better than those of the controls. These data show that nitrile polymers could be modified with a lower molecule weight mercaptan with no loss of properties but with a considerable saving in amount of modifier. Mercaptans are essential for the initiation of butadiene–acrylonitrile in the presence of persulfate at 50°C. For the hot nitrile rubber preparations, the series of mercaptan from t-C₁₀ to t-C₇ are efficient modifiers. However, the heptyl and octyl mercaptans are retarders, and the t-C₉ and t-C₁₀ are the preferred modifiers for efficiency and unretarded polymerization. The modification with a series of mercaptans ranging from t-C_13.2 to t-C₈ of 75/25 styreneacrylonitrile at 50°C. in presence of persulfate–bisulfite showed a consistent behavior. The transfer constant decreased in a regular manner as the molecular weight of the mercaptan increased, and for the series of tertiary modifiers the t-C₁₀ mercaptan was the most efficient as judged by a melt flow test.     

MECHANISMS OF THE GAS-PHASE REACTIONS OF AROMATIC HYDROCARBONS AND PAHS WITH OH AND NO 3 RADICALS

Chemical removal for the simple monocyclic aromatic hydrocarbons (benzene and the C ₁ -C ₃ alkylbenzenes) and naphthalene and the C ₁ -C ₂ alkylnaphthalenes in the atmosphere is by reaction with hydroxyl (OH) radicals. Naphthalene and the C ₁ -C ₂ alkylnaphthalenes may also be removed, but to a much lesser extent, by reaction with nitrate (NO ₃ ) radicals. While rate constants for the gas-phase reactions of OH radicals and NO ₃ radicals with many of the simple monocyclic aromatic hydrocarbons and with naphthalene and the C ₁ -C ₂ alkylnaphthalenes have been measured, the detailed mechanisms of these OH radical-and NO ₃ radical-initiated reactions in the atmosphere are less well understood, especially for naphthalene and the alkylnaphthalenes. Here we present the available data on the reaction mechanisms occurring under laboratory conditions and attempt to reconcile these data with ambient atmospheric measurements. The OH radical reactions with benzene and alkylbenzenes and the OH radical and NO ₃ radical reactions with naphthalene and alkylnaphthalenes proceed mainly by initial addition of the OH or NO ₃ radical to the aromatic ring(s) at room temperature and below. The NO ₃ radical reactions with alkylbenzenes proceed by H-atom abstraction from the C-H bonds of the alkyl substituent group(s), while the NO ₃ radical reactions of naphthalene and the alkylnaphthalenes proceed by addition and with rates proportional to the NO ₂ concentration. The OH-monocyclic aromatic adducts react with O ₂ under atmospheric conditions, while the OH-naphthalene/alkylnaphthalene and NO ₃ -naphthalene/alkylnaphthalene adducts appear to undergo significant reaction with NO ₂ under urban atmospheric conditions.     

Contribution of the γ-hydroxy group to the β-O-4 bond cleavage of lignin model compounds in a basic system using tert-butoxide

Abstract

The most common non-phenolic β-O-4-type lignin model compounds with or without the γ-hydroxymethyl group (C₆-C₃- or C₆-C₂-type, respectively) were treated in a 0.5?mol/L potassium tert-butoxide in DMSO solution at 30?°C to examine the effects of presence of the group. The β-O-4 bond of the C₆-C₃-type cleaved more rapidly than the C₆-C₂-type, indicating that the γ-hydroxy group contributes to the cleavage, in contrast to their reactions in alkaline pulping processes. Furthermore, the β-O-4 bond of the threo isomer of the C₆-C₃-type cleaved more rapidly than that of the erythro isomer. This result can be attributed to the fact that the erythro isomer has the hydrogen bond between a generated alkoxide and the other hydroxy group at its α- and γ-positions in its most-preferential conformer, interfering with the β-O-4 bond cleavage. It was also suggested in treatments of their methyl-etherified derivatives at the α- or γ-hydroxy group that the contribution of the γ-hydroxy group of the threo isomer is greater than that of the erythro isomer. Detailed examination of the distribution profile of reaction products supported this greater contribution of the γ-hydroxy group of the threo isomer.     

Antistatic and wetting properties of chemodegradable cationic surfactants containing 1,3-dioxolane moiety

In this paper we report some performance properties of [(2-alkyl-1,3-dioxolane-4-yl)methyl]trimethylammonium bromides (C _n -D-TAB, where C _n =n-C₉H₁₉, n-C₁₁H₂₃, n-C₁₃H₂₇), [(2,2-dialkyl-1,3-dioxolane-4-yl)methyl] dimethylammonium bromides (C _n C _m -D-TAB, where C _n =n-C₈H₁₇, n-C₁₀H₂₁ and C _m =CH₃ or C _n =C _m =n-C₆H₁₃), in relation to classical alkyltrimethylammonium bromides (C _n -TAB, where C _n =n-C₁₂H₂₅, n-C₁₄H₂₉ or C₁₆H₃₃) and dialkyldimethylammonium bromides (C _n C _m -DAB, where C _n =C _m =n-C₁₀H₂₁ and C₁₂H₂₅). Antistatic properties were measured by means of surface resistance (R _s), half charge decay time τ_1/2, and maximal voltage induced (U _ind) on polyethylene (PE) film and polypropylene (PP) nonwoven fabric. Wetting ability is reported as the concentration of surfactant necessary for immersion of a cottonfabric ring in 100 s, according to the Polish Standard PN-74/C-04800. All acetal-type surfactants showed the antistatic effect. The best results were given by C₉-D-TAB [R _s=8.5·10⁷ (PE), 1.1·10⁸ Ω (PP); τ_1/2=0.25 (PE), 0.30 s (PP); U _ind=205 (PE), 220 V (PP)] and C₁₁-D-TAB [R _s=8.7·10⁷ (PE), 1.3·10⁸ Ω (PP); τ_1/2=0.25 (PE), 0.30 s (PP); U _ind=190 (PE), 340 V (PP)] in relation to pure PE foils and PP fabric: R _s=3.0·10¹⁴ (PE), 9.8·10¹⁴ Ω (PP); τ_1/2=>600 (PE), >600 s (PP); U _ind=985 (PE), 940 V (PP). Both C₉-D-TAB and C₁₁-D-TAB indicate similar degrees of antistatic ability compared to C₁₀C₁₀-DAB. All C _n -TAB compounds do not show any antistatic effects. It was concluded that addition of the 1,3-dioxolane moiety to the hydrophobic tail of quaternary ammonium salts promotes both antistatic and wetting properties. Additionally, methyl or n-hexyl group incorporation at the C-2 carbon atom in the 1,3-dioxolane ring significantly decreases the surface conductivity.     

Determination of the Specific Heat of the Normal Alkanes C<Subscript>7</Subscript>-C<Subscript>11</Subscript>

Using precise experimental data on the specific heat at constant pressure C _p of the normal alkanes C₇-C₁₁ over a wide parameter range, the C _p values are determined on the liquid and vapor branches of the boundary curve from the normal boiling point to 0.98T _c. In the coordinates C _p-P _s-T _s, orthogonal projections of the reduced phase diagram of these hydrocarbons are constructed and analyzed. Existing generalized expressions for C _p of the liquid and gas phases of the normal alkanes C₅-C₁₁ on the boundary curve as a function of temperature are evaluated, and new expressions for C _p are proposed.__________Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 4, 2005, pp. 476–480.Original Russian Text Copyright © 2005 by Kuznetsov, Gorbachev.     

Adsorptive and stripping behavior of methylene blue at gold electrodes in the presence of cationic gemini surfactants

The adsorptive and stripping behavior of methylene blue (i.e. methylene blue chloride, MB) at a gold electrode has been studied with voltammetry, alternating current impedance spectra (ACIS) and quartz crystal microbalance (QCM). MB exhibits a pair of cyclic voltammetry peaks at about −0.3 V (versus SCE) in 0.05 M pH 6.9 phosphate buffer solutions. In the presence of cationic gemini surfactants such as C₁₆H₃₃N(CH₃)₂-C₄H₈-N(CH₃)₂C₁₆H₃₃Br₂ (C₁₆-C₄-C₁₆), C₁₆H₃₃N(CH₃)₂-C₄H₇OH-N(CH₃)₂C₁₆H₃₃Br₂ (C₁₆-C₄OH-C₁₆), C₁₆H₃₃N(CH₃)₂-CH₂-C₆H₄-CH₂-N(CH₃)₂C₁₆H₃₃Br₂ (C₁₆-ph-C₁₆) and C₁₆H₃₃N(CH₃)₂-C₁₂H₂₄-N(CH₃)₂C₁₆H₃₃Br₂ (C₁₆-C₁₂-C₁₆), the anodic peak grows rapidly and moves in positive direction, but the cathodic peak gradually decreases, due to the association adsorption and electrostatic interaction of the geminis with MB and its reduced product (i.e. leuko methylene blue, LMB). With the aid of geminis the adsorption amount of MB increases under open-circuit, but the impedance of the mixed adsorption film to Fe(CN)₆^3−/4− almost keeps unchanged, compared with either bare gold electrodes or MB film, while the adsorption film of geminis exhibits greater impedance. This probably is due to the electron medium action of MB in the film. Gemini surfactants with same alkyl-chain (i.e. -(CH₂)₁₅CH₃) but different molecular structure, exhibit different influence. The enhancing action of geminis studied follows such order as: C₁₆-ph-C₁₆ > C₁₆-C₄-C₁₆ > C₁₆-C₄OH-C₁₆ > C₁₆-C₁₂-C₁₆. The change of peak potential was ascribed to the interaction between MB and surfactants, as well as the blocking action of surfactant film. For comparison, the influence of dihexadecyldimethylammonium bromide (DCAB) and cetyltrimethylammonium bromide (CTAB) was studied, and the influence of other factors is discussed as well.     

Photodegradable polymers. II. Preparation of styrene copolymers with alkyl and phenyl β-styryl ketones and their photodegradability

Photodegradable polymers having pendent carbonyl groups attached directly to the polymer chain were prepared by copolymerization of styrene (St) with alkyl and phenyl β-styryl ketones (RCOCH?CHC₆H₅), where R = CH₃, C₂H₅, n-C₅H₁₁, n-C₁₁H₂₃, t-C₄H₉, cyclo-C₆H₁₁, and C₆H₅. The photodegradability of these copolymers was traced by viscometric and IR spectroscopic measurements. The degradability of St–benzalacetophenone (BAPh) copolymer is greater than that of St–alkyl styryl ketone copolymers under the irradiation of a high-pressure Hg lamp. The photodecomposition behavior St–BAPh copolymer was investigated in detail by a spectoirradiation technique. The changes in molecular weight and its distribution by photodegradation were measured by gel permeation chromatography, and the quantum yield for bond scission along the main chains of the copolymer was estimated to be about 5 × 10^?3 by 328 nm irradiation in a benzene solution. Examination of the effect of wavelength of the radiation on the bond scission showed that 328-nm light is most effective. The photochemical degradation process was shown to occur chiefly via triplet state of carbonyl groups by the quenching technique using 1,3-cyclohexadiene as a triplet quencher. The quantum yield of decarbonylation process was also estimated to be about 4.2 × 10 ^?2 in benzene.     

Influence of precuring on high pressure steam hydration of tricalcium silicate in the presence of other constituents of portland cement

The influence of precuring at room temperature on the autoclave hydration of C₃S in the presence of other constituents of clinker and of gypsum was studied. C₃A, C₄AF and β-C₂S hampered the formation of C₃SH_1.5 and, especially for short precuring times, favored the formation of α-C₂SH. Gypsum hampered the formation of both the crystalline hydrated silicates. When the steam treatment took place after a long precuring, C-S-H was the prevailing hydrated silicate formed.     

Scientific foundations of preparation and technologies of production of the catalysts of reforming of gasoline fractions: Development of the process technology

The article summarizes the results of development of the scientific foundations of preparation of the catalysts, and of the experimental development works on creation of the new technologies of their production with the use of physical models, which were previously created on the basis of fundamental research. The results of the adoption of the new production technologies of the reforming catalysts of the PR series at the domestic plants are presented. The adoption consisted in creation and approbation of the fundamentally new technologies of production of the aluminum hydroxide (AHO) by means of the continuous method, modification of AHO by the elements of IV group, plasticization and forming of AHO in the production of the support, application of H₂PtCl₆ using the reactions of the ligand substitution of C⁻ by the functional groups of the support, and reduction and activation of the catalyst, which provide the optimal chemical com- position. Their operation during the 15-year period is analyzed. The reasons of high selectivity (up to 90%) of the new catalysts are found; the new technologies of the combined processing of mixture of C₃-C₄ alkanes with C₅₊ are developed and tested for the production of the high-octane catalysts with selectivity approaching 100%. The main effect of the C₅₊ yield increase of the end products is achieved by the transformation of the C₃-C₄ alkanes into the more high-molecular aromatic hydrocarbons. New processes of the combined processing of the mixtures of C₃-C₄ and gasoline fractions can be considered to be an alternative technology, which solves the important task of broadening the source of raw materials of the motor fuels by the inclusion of the C₃-C₄ alkanes of little value into the processing.     

Influence of Fe2O3 on the hydration kinetics of tricalcium aluminate

The influence of Fe₂O₃ on the hydration kinetics of tricalcium aluminate (C₃A) was studied in order to clarify the mechanism of improving hydration resistance of CaO by in-situ synthesized tricalcium aluminate. The Krstulovic-Dabic model was used to investigate the hydration processes of Fe₂O₃-C₃A solid solution and calculate the corresponding kinetic parameters. The hydration products were analyzed by the X-ray diffraction and scanning electron microscope. The results indicated that the Krstulovic-Dabic model simulated the hydration processes of Fe₂O₃-C₃A solid solution at different stages effectively. The hydraulic activity of Fe₂O₃-C₃A solid solution decreased with the addition of Fe₂O₃. Reasonable amount of Fe₂O₃ addition reduced the hydration rate in the initial stage of Fe₂O₃-C₃A solid solution hydration, while the hydration rate of Fe₂O₃-C₃A solid solution was increased with excessive amount Fe₂O₃. The hydration process was controlled by multiple mechanisms due to an incomplete layer of hydration products was formed on the surface.     

Hydrotreatment of jatropha oil over noble metal catalysts

Jatropha oil is a promising nonedible feedstock for producing renewable diesel. In this work, the hydrotreatment processing of jatropha oil was investigated. Instead of using conventional alumina-supported Co–Mo, Ni–Mo, and Ni–W catalysts that need sulfidation pretreatment, noble metals such as Pd and Ru were chosen. Trials were performed in an isothermal trickle-bed reactor and the reaction conditions were as follows: temperature 603–663?K, weight hourly space velocity (WHSV) 1 to 4/h, pressure 1.5–3?MPa, and H₂/oil ratio 200–800 (v/v). Yield of n-C₁₅ to n-C₁₈ hydrocarbons was maximized (70.3 and 43.8% for Pd/Al₂O₃ and Ru/Al₂O₃, respectively) at the following conditions: T?=?663 K, WHSV?=?2/h, P?=?3?MPa, and H₂/oil ratio?=?600 (v/v). Since Ru favored cracking reactions to a larger extent than Pd, the yield of C₁₅ to C₁₈ hydrocarbons over Ru/Al₂O₃ was lowered. Using simple first-order plots for oil conversion, activation energies for the hydrotreating process over Pd/Al₂O₃ and Ru/Al₂O₃ were found and they were equal to 109 and 121?kJ/mol, correspondingly.     

Synthesis of stereoblock poly(methyl methacrylate) via transformation of isotactic-specific living polymer anion to syndiotactic-specific anion

Polymerization of methyl methacrylate (MMA) by isotactic poly(methyl methacrylate) (PMMA) living anion, prepared with t-C₄H₉MgBr in toluene at ?60°C, was carried out at ?78°C in the presence of trialkylaluminiums (R₃Al; R = CH₃, C₂H₅, and n-C₄H₉) to obtain a stereoblock PMMA, isotactic PMMA-block-syndiotactic PMMA. Among the R₃Als, (CH₃)₃Al gave most effectively the steroblock PMMA with narrow molecular weight distribution. The fraction of rr triad in the syndiotactic PMMA block increased with increase in the ratio of Al/Mg and reached about 76% at a ratio of Al/Mg ≥ 6. The method was also used to prepare stereoblock copolymer comprising isotactic PMMA block and syndiotactic block of butyl methacrylate. Stereocomplex formation and solution viscosity of the stereoblock PMMA were also studied.